On Thu, 6 Nov 1997 10:50:12 -0600 philk5pc@connect.net (Phil Clements)
writes:
>At 09:18 AM 11/6/97 EST, you wrote:
>>
>>A competent tech can copy that circuit in 10 minutes and generate a
>>schematic. There are only 20 components on the PC board and 12 of
>them
>>are the filter.
>
>The schematic usually lists the parts and what they are, and who makes
>them. I am sure ZJ makes no in-house parts and that all are available
>over-the-counter locally.
A company that is not trying to hide their sources usually does this and
is very much appreciated by us fix-it types.
Except for the MCL MMIC's the ZJ box uses parts available thru Mouser and
DigiKey. All the components used are marked with standard industry codes
so I fail to see why a schematic is not included. Sounds childish IMO.
I should have made myself more clear; I
>did draw a schematic, but have no idea about the parts.
The caps are clearly marked with values and the inductors use standard
color codes. Maybe I'm missing something here but ......???
There is even
>a great debate on the MMIC's...which one to buy.
It depends on what one you have. I'll repeat what I posted a few months
ago for MCL MMIC identification. There are 2 codes used; alpha numeric or
color.
MAR-1 AO1 Brown
MAR-2 AO2 Red
MAR-3 AO3 Orange
MAR-4 AO4 Yellow
MAR-6 AO6 White
MAR-7 AO7 Violet
MAR-8 AO8 Blue
I have only identified 4 varieties sofar in ZJ boxes. Please be aware
that each MMIC has its own unique bias requirements and the wall warts
that are shipped plus the 1/2W resistor on the PC board are matched for
that device.
>
>
>>Very true and the antenna signal levels are much lower than on a long
>>Beverage. After all it is sold as a Beverage Box...not a EWE box; at
>>least in the literature I have here.
>
>It would have been very difficult to name the box a "EWE" box, as the
>EWE
>had not yet been invented when the ZJ box came out!
OH? the ZJ came out in 1994 I thought....at least the PC board has that
date and the first I heard of it was Dayton that year.
The EWE was "published" when? It was discussed on 75M long before its QST
debut. Floyd was always running tests.
>>At this QTH I am surrounded with 5KW BC stations in the 3 to 10 mile
>>range and most of them are above 1400KHz. The IMD generated in all of
>the
>>ZJ boxes repaired here make 160M useless for weak signal DXing.
>Perhaps
>>if I were to build a BC filter properly matched to the ZJ input
>impedence
>>it would help.
>>The ZJ filter is after the 9:1 xfmr and before the MMIC. The 9:1 xfmr
>has
>>both input and output windings to a common ground and all other
>grounds (
>>filter, DC bypass, etc) are also common on the PC board. This is
>asking
>>for ground loop problems. As mentioned here previously by many
>others
>>that is a poor way to operate a Beverage.
>
>I have never even seen a beverage...must be nice! No ground loop, IMD,
>overload, BCI, or any other negatives here on the EWE/ZJ.
>>
>>I have another ZJ box here for repair that I have not even opened the
>>shipping box yet.
>>I'll be glad to run some tests....any suggestions?
Well, I opened it. This beast has a MAR-1. It is fried plus the balun
xfmr plus 2 of the series filter inductors. BTW, the "protection" IMD
generator diodes are fine. The customer has agreed to a FT114-61 xfmr and
a 2N5109 "conversion" since this is the 3rd time he fried it.
>You beverage users are in another league from us "EWE'ers.
I cant even imagine living on a postage stamp lot! Minimum lot size here
is 1acre.
A 3 BR, 2 bath, 2 car garage, and full basement home is selling for
$95K. Others go into serious 6 digits but I am only 30 miles fm downtown
Boston so lots of yuppies are finding this small town.
..all my
>testing
>is complete here, and in my situation, the EWE/ZJ is the best RX
>antenna
>I have ever had.
We all use what we can.
73 Carl KM1H in NH ; no sales tax, no state income tax and very few
antenna regulations.
>
>(((73)))
>Phil, K5PC
>
>
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>
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